I have Shimano on both of my bikes. I rode SRAM on a rental bike for a week. I like them both, they shifted when I pushed whatever action was required of me. I've never tried Campy stuff, but the people who use it remind me of vegans or people who back into parking spots (annoying) so I will avoid Campy out of general principles. I kid, I kid, I like Shimano plenty. I'll just stick with that.